Hi Simon,
I do not know whether my sentences are grammatically correct?!

-Petrol and other energy sources play significant role in prosperity of countries. If the government increased the price of fuel, traffic congestion and environmental problems would be declined

-Video games leave an unconscious impression on development of adolescents’ social skills. If the more educational electronic games were available, the parents would be easily able to understand their benefits

To my vantage point, the amount of unscatted heritage sites in a country can help a community to boost their financial situation. If government tries to keep the historical monuments in better modern condition, it will definitely increase the amount of keen tourist in a society.

In my opinion, government ought to give strict punishment to criminals to reduce the rate of re-offences.If the environment in the jail were more painful and restricted, the offenders would think twice before perpetrating a crime again.